Contact plate freezers, because of their high efficiency in energy usage, have been extensively used in commercial food processing plants to freeze prepackaged foods which are of the type customarily offered for retail sale in the frozen food section of a supermarket or the like. Such freezers, however, have heretofore been restricted to handling products which are disposed in rectangular or square shaped cartons of various thicknesses, lengths and widths and formed of a rigid or semirigid material. The need for such shaped cartons is that as they are fed through the freezer the prepackaged products are pushed against one another. In the operation of the freezer, the prepackaged (carton) product is contacted by upper and lower refrigerated plates and is subjected to substantial vertical load because it supports the plates disposed thereabove. After the freezing has been conpleted the prepackaged products have a tendency to freeze onto the plates and therefore must be broken loose, when the plates are spread apart, by a pusher bar which pushed against the frozen packages disposed between the plates. The carton also serves to shield the product from direct contact with the refrigerating plates.
To enhance the esthetics and at the same time reduce the cost of the frozen product, cartons or containers of a variety of types, shapes and sizes have been utilized with the result that pushing of such packages against one another while being fed through the freezer has produced disastrous results. For example, a very common container used in the packaging of convenience foods is an aluminum drawn tray or plate having outwardly flared, or divergent, sidewalls terminating in a laterally extending flange or lip. If an attempt is made to shove or push one of these containers against another, the lip of one container will ride up against the other causing an overlap or one container will ride over the other. If the container is a plate, such relative movement between abutting containers will likely cause damage or severe distortion of the containers and spillage of the products resulting in contamination of the equipment. In addition, when the containers are severely distorted and/or ride over one another, a serious jamming problem will develope requiring a complete shutdown of the equipment for a substantial period of time to allow at least partial thawing of the jammed packages. The time loss and the product spoilage resulting from such shutdown are serious and, therefore, the use of contact plate freezer when handling such products has been avoided or at most significantly curtailed, notwithstanding the energy efficiency of such a freezer.